带有热插拔代理的 Weblogic Server

Question

We are looking a free alternative for jRebel. It seems hotswap agent is a free good alternative for jRebel. But I didn't sure about it supports weblogic server, is there anyone use hotswap agent with weblogic server and how?

Answer 1

DCEVM and HotswapAgent do not support Weblogic. Maintainers are clear about that, it is mentioned in many issues: here , here andhere .

So if you are looking for a solution that will flawlessly work out of the box on WLS, is up-to-date and supported for recent java versions, then I'm afraid DCEVM is not one.

But if your are ok with unsecure , hacky solution, then read on.

The first problem with dcevm and weblogic is to even get it running. I tested weblogic docker image with dcevm + HotswapAgent and most combinations of oraclejdk and dcevm versions cause error or other JVM/WLS crash on startup. Long time ago the maintainers said oraclejdk should work with dcevm, but I guess this is not actively supported/tested and just works by coincidence on some combination of versions. Deep magic used by WLS doesn't help also.

But thanks to some comments I found WLS will start on these two:

• oraclejdk 1.8.0_05 + dcevm installer-light-jdk8u5.52.jar (25.5-b02-dcevmlight-58)
• oraclejdk 1.8.0_25 + dcevm DCEVM-light-8u45-installer.jar (25.45-b02-dcevmlight-15

NOTE: These versions are ancient and probably have lots of security vulnerabilities, use at your own risk.

procedure:

• overwrite original java /u01/jdk/ in the image,
• take linux_amd64_compiler2/product/libjvm.so from dcevm installer and put it in /u01/jdk/jre/lib/amd64/dcevm
• add -XXaltjvm=dcevm to weblogic commandline.
• (optionally) to get HotswapAgent features:
  • add hotswap-agent-core.jar or hotswap-agent.jar in /u01/jdk/jre/lib/amd64/hotswap together with option -javaagent:/u01/jdk/jre/lib/amd64/hotswap/hotswap-agent.jar on wls commandline
  • add hotswap-agent.properties to your war/ear/classpath

Now run a remote debugging session, modify a class by adding a new method and recompile - hotswapping new method is not supported by standard hotswap, it will only work when dcevm is active.